Form is temporary, class is permanent. Or so the adage goes. If that's the case, and the bookmakers clearly feel so, then Roger Federer has a favourite's chance of defending the ATP World Tour Finals title.

Federer, 285 weeks as world No. 1, has had a disappointing year by his lofty standards. He has slipped to No. 4 in the world and will end the season without a major trophy in his cabinet. But for a couple of key moments, though, it could have been different for Federer at the majors. He squandered match points against Novak Djokovic at the US Open and let a two-set lead slip against Jo-Wilfried Tsonga at Wimbledon. But he has shrugged off those setbacks in recent weeks, backing up a win at the Swiss Indoors by taking the BNP Paribas Masters - joining Andre Agassi as the only two men to have won both the Paris Masters and French Open.

Confidence is once again coursing through the Swiss and the graceful elegance has been on show during a 12-match unbeaten run. But does he justify his billing as the 15/8 pre-event favourite with bet365?

His wins in Basel and Paris came without him playing any of the top three in the world, so a case can be made for him being underpriced. To counter that, he did look in supreme form against Tsonga and has the added incentive of knowing victory at the O2 will take him to six wins at the year-end championships and past Ivan Lendl and Pete Sampras.

Betting bullets

Andy Murray to win the Tour Finals - 5/2 at bet365Andy Murray to win Group A - 10/11 at bet365

But in a tournament containing the top eight in the world, it is no easy task negotiating your way through the group stage. Federer has the advantage of guaranteed fitness and form. Alongside him in Group B are Rafael Nadal, Tsonga and Mardy Fish. Despite losing to Tsonga at Wimbledon, Federer appears to have his measure and the event is likely to prove one too many for Fish. The American has had a great year, but he retired against Juan Monaco in Paris and is likely to be swept aside.

Nadal is an intriguing case as it is far from clear what sort of form he is in. Yes the Spaniard won the French Open this year, but he has not looked in good form for well over 12 months. He has not played since his defeat to Florian Mayer in Shanghai at the start of last month. Also counting against Nadal is that he has never mastered the indoor surface. He did reach the final 12 months ago, but was at the top of his game at that point. Nadal is available at 5/1 with bet365, a price that would look attractive if he can hit form. But that's a big if.

Group A is as intriguing as Group B, with Novak Djokovic arriving in London arguably under a greater cloud than Nadal. The Serb has carried all before him this year, winning three of the four grand slams, but he has not looked in the same form since battling through injury to claim the US Open. He pulled out of the Paris Masters with a shoulder injury, but pocketed a £1 million bonus first, and it is to be seen how close to 100% he is.

If there are any chinks in his armour they will be exposed by arguably the most in-form player in the game at the moment: Andy Murray. Prior to losing to Tomas Berdych in Paris last week, Murray had won 18 matches on the spin spanning three tournament victories.
Murray faces no easy task, as even a 75% fit Djokovic will be a stiff challenge and he has a losing record against Berdych. But he can kick off his campaign with a win over David Ferrer, who seemingly has no way of fending off Murray, and from there he can take momentum.

The British No. 1 is still smarting from his defeat to Nadal in the semi-finals 12 months ago, but you get the impression that if they meet again it will be Murray who comes out on top. Provided he wins his group, and Federer does the same, those two can sweep through to the final and spurred on by home support this could be Murray's chance to claim the biggest win of his career.

Please note that odds are correct at time of publication and are subject to change.